Twisting and winding of textile fibers



Aug. l5, 1950 E.. c. PFEFFER, JR., Erm. 2,518,491

I TWISTING `AND WINDING OF TEXTILE FIBERS 3 Sheets-Sheet l l)/)/ Aug. l5, 1950 E. c. PFEFFER, JR.. Erm.

'rwls'rING AND WINDING DF TEXTILE FIBERS Filed July l, 1948 Y 3 Sheets-Sheet 2 Flc; 3 54 5 y 3o. 9 D f s4 67 j, l 63 .-.l i5 I 7 62 29 ZM/M69 27 L \f W 23 2284- \7 6\ "2" 26 6| INVENTORS 43 EDWARD C.PFEFFER,JR.

.JOHN J. GANNON JOHN J. FISDELLA Aug l5, 1950 y E. c. PFEFFER, JR.. l-:rAL 2,518,491

TWISTING AND WINDING OF TEXTILE FIBERS Filed July l. 1948 SSheets-Sheet 3 INVENTORS EDWARD C. PFEFFER,JR.

JOHN J. GANNON JOHN J. FlSCELLA BY@ Q Patented Aug. l5, 1950 UNITED STATES Y orales 2,518,491 'rwls'rrNG Ann wrNnrNo or rnx'rnr. maas Edward C. Pfeffer, Jr., and John J. Gannon, Troy, and John J. Fiscelia, Menands, N. Y., assignors to Cluett, Peabody and Company, Inc., Troy, N. Y., a corporation of New York Application uly l, i948, Serial No. 36,476

3 Claims. (Cl. 57-58) improve and simplify twisting and winding apparatus and methods for textile fibers.

` Another object of the invention is to provide an improved method and apparatus for twisting and winding yarns, groups of nlaments, and/or iong bundles of textile iibers on a bobbin to form a package; which enables the winding of either large, mediumror small packages with the same elciency and effectiveness; with which thread, filaments, yarns or bundles of fibers may be wound in progressive turns and superposed layers on a bobbin with a desired degree of tautness; with which the winding may take place for relatively long periods with a minimum of attention from an operator or attendant; with which breakage of the threads, filaments, yarns or fibers being wound on the bobbin will be a minimum; and with which rapid rotation of the bobbins in the event of mechanical trouble will be automatically prevented.

Another object of the invention is to provide f an improved method and apparatus for imparting about a two for one twist to a yarn, thread, #bundle of textile `iibers or laments, in a rapid' continuous operationV and handling; also for winding the twisted yarns, threads, filaments or fibers onabobbin to form a package; Awhich will handle the laments or fibers by twisting or winding them at least as rapidly as by any previous methods and apparatus for twisting and winding textile materials; with which the fibers or filaments being wound on the bobbin may be wound in helical form and superposed layers, or as frusto-conical superposed layers that have a somewhat telescoping or nesting relation to each other, and which layers progress in a direction from end to end of the bobbin.

Anotherobject of the invention is to provide improved apparatus for accomplishing each o1' these objects, and which will be relatively small, compact, durable, convenient, inexpensive, and of relatively large capacity.

Other. objects and advantages will be apparent from the following description of one embodiment of the invention, and the knovel features ,l thereof will be particularly pointed out hereinafter in connectionwith the appended claims.

2 In the accompanying drawings: Fig. 1 is a side elevation, partly in section and partly schematic, of apparatus constructed in accordance with this invention and useful in practicing the method;

Fig. 2 is a vertical central, elevation of part of the twisting and winding mechanism of the same;

Fig. 3 is a similar elevation on a larger scale of a part of the mechanism shown in Fig. 2;

Fig. 4 is a plan of the mechanism shown in Fig. 2, but with the winding member and the bobbin removed from the spindle.

Fig. 5 is a' plan of part of the mechanism of Fig. 4 but with the safety stop in a diiierent or operative position; and

Fig. 6 is a side elevation of the parts shown in Fig. 4, but partly in section in order to show details of construction.

In the illustrated embodiment of the invention, and referring first particularly to Fig. l, the invention is illustrated, by way of example, as part of a mechanism for drawing rovings of staple bers to form a twisted, yarn and winding the yarn on a bobbin. For this purpose the drawing mechanism is of a suitable roller type, designated generally at I, which is mounted on a roll stand 2 on a roll beam 3. The beam frame 3 is provided on a suitable main frame 4. A creel or bobbin stand 5, is mounted on the upper part of the frame 4, and rotatably supports a plurality of vertically disposed bobbins 6, on which are wound the rovings 1 and 8 of staple iibers, which are to be drawn and combined into a yarn 9 and then twisted and wound on a bobbin, to form a package. 'I'he rovings l and 8 are unwound from the bobbins 6 and passed together, side by side, through the roller drawing device l, where they are combined and drawn into a yarn 9, which operation frequently is called spinning from double roving. Any number of rovings may be combined in this manner to make each strand of yarn. The roller drawing device l is provided with consecutively arranged pairs of rollers operating at progressively higher speeds, and the rovings pass between the rollers of each pair in succession.

The drawn, combined rovings are conducted as a yarn 9 through a guide or eye l0 carried on a rod I l projecting from the roll beam 3. This is a typical drawing mechanism in common use, and it has, therefore, been illustrated only rather schematically, since any suitable drawing mechanism may be employed. The drawing rollers are driven by a suitable mechanism (not shown) in the proper speed ratios for the successive pairs,

with power for kdriving them obtained from a |3 which in turn meshes with and is driven byv a pinion |4.

The pinion I4 is coupled to a larger gear I5 concentric therewith which meshes with and is driven by a pinion I6 which is in turn concentric with and coupled to a gear |1 that meshes with a gear I6 fixed on the shaft |9. The gears and pinions I2 to I1 are suitably mounted for rotation, but since such driving mechanisms are old and the details thereof may vary considerably, this driving mechanismis shown rather schematically. The shaft I9 is driven from any suitable source of power (not shown) such as an electric motor, and this shaft kthrough the driving connection represented schematically by the meshing gears I2 to I8, will drive the gear I2 at a lower rate than the shaft I9. Any other suitable speed reducing mechanism may be employed between the shaft I9 and the roller drawing mechanism I.

Disposed a short distance below and aligned with the guide Illv is a twisting and winding device designated generally at 20. This device 29, shown in sectional elevation in Fig. 2, is mounted on a. support or platform 2| so as to upstand therefrom. Disposed in a passage in the support 2| (Fig. 2) is a bearing member 22 with a. flange l23 on its upper end which overliesthe support 2|. Adjacent to its upper and lower ends this member 22 is provided, in its interior, with vertically spaced and aligned anti-friction or ball bearings 24 and 25, which rotatably support a sleeve 26 that passes upwardly through the sup-v port 2| and the member 22. One of these bearings, such as the upper bearing 24, is a combined radial and thrust bearing, and its inner race engages against a downwardly facing shoulder 21 on sleeve 26 which supports the weight of the sleeve 26. The outer race of bearing 24 engages against a shoulder 26 provided in the passage or interior of the member 22, which holds the bearing in position and transfers the weight of the sleeve 26 to the member 22.

Above the flange 23 (Fig. 2) the sleeve 26 is provided with a peripheral flange 29 which supports a disc or plate 30 that has a central aperture telescoping over the sleeve 26. Disposed above the disc 30 and around the upper end of the sleeve 26 is a tubular member 3| which telescopes downwardly over the upper end of the sleeve 26 and in spaced relation thereto. This member 3| is part of a bobbin support and is' Arotatably supported on the upper end of the sleeve by vertically spaced. ball or anti-friction bearings 32 and 33. These bearings 32 andv 33 are also combined radial and end thrust bearings. and the lower bearing 34 has its inner race resting on an external shoulder 34, facing up'- wlrdly, of the sleeve 26, a 'short distance from its upper end. The outer race of that bearing counter-sunk into the chamber of the member I at its lower end, and seats against a shoulder 33 thereof. The outer race of the upper bearhg 32 seats against a. shoulder 36 within the chamber of the tubular member 3|. l

A lock nut 31 is threaded upon the periphery the upper end of the sleeve 26, and overlies the upper bearing 32 so as to confine the member 3| to the sleeve 26, and a similar lock nut 33 is threaded upon the lower end of the sleeve 26, but some distance above its extreme lower end, and engages against the inner race of the bearing 25. Fixed on the lower end of the sleeve 26 is a driving pulley '39 which is driven by a belt 40, which in turn is driven by a pulley 4I. see Fig. 1, fixed on the main shaft |9.

Fixed upon the periphery of a reduced lower end of the member 3|, (Fig. 2) is a plate or disc 42 which lies in close proximity to, but is spaced slightly above, the upper face of the disc 39. A spindle 43 passes upwardly through the sleeve 26 and well above and below it, and is rotatable and slidable in the sleeve except as they are coupled for rotation together in a manner which will be hereinafter explained. The spindle 43 rises well above the member 3|, and rotatably confined on this upper rising end of the spindle is a tubular bobbin support 44 which is provided adjacent its lower end with a laterally extending flange 45 that rests upon the upper end of the member 3|, to which it is secured,

such as by screws 46, see Fig. 4. 'I'he ange 45 may have. depending from its lower face, an annular ring 41 (Fig. 2) which telescopes within the open upper end of the member 3| and which serves to accurately locate the bobbin support on the spindle, since the bobbin support does not closely fit the spindle but is preferably provided-with substantial clearance from the upper end of the spindle. v

The exterior of the bobbin support 44 is formed to receive and detachably support a suitable bobbin 46 on which the thread, filaments, or bers are to be wound, and preferably the exterior surface of the lower end of the bobbin support is upwardly tapered slightly as at 49, and the bobbin preferably has a similarly tapered seat or socket that serves to locate and support it and provide a frictional drive between it and the bobbin support. The upper end of the spindle extends substantially above the upper end of the bobbin support 44, and telescoped within this upper end of the spindle 43 is a tube 50 which is frictionally fitted to, although detachable from, Vthe spindle. This tube 50 rises above the upper end of the spindle and there mounts a cap 5| which telescopes over the upper end of the tube 50. The cap 5| is rotatably confined on the upper end of the tube 50 by a connection which is preferably of relatively low friction, such as vertically spaced ball bearings 52 and 53. The cap 5|,is thus rotatably mounted, by the ball bearings `52 and 53, on the upper endv of the tube 50 that is frictionally coupled to the upper end of the spindle.

'I'he cap 5| and the tube 50 are firmly coupled through the bearings so that by lifting the cap, the tube 50 may be pulled from the spindle. The cap 5| is provided with a passage 54 at its upper end which is vertically aligned with, and forms a continuation of, the passage of the tube'SIl. Secured to the lower end of the cap 5| at its periphery is a sleeve 55 which telescopes downwardly over the upper end of the spindle and the upper end of the bobbin. Diametrically opposite and downwardly diverging rods 56 and 51 depend from the lower end of the sleeve 55, and at their lower ends terminate in thread guides or eyes 56. A ring 59 surrounds the spindle and is secured to the lower ends of the rods 56 and 51 so as to form therein a unit, with the eyes 56 preferably below the ring 59. The diameter of the ring 53 is greater than the maximum expected diameter of the completed package on the bobbin.

The spindle 43 is provided with a passage 6I) (Figs. 2 and 3) that extends downwardly from ,siasoi `the upper end of the ,spindle to a position well below the upper end oi' the sleeve 26, and, for a considerable length from its lower` end,"this passage 66 opens sidewise through the spindle to form a vertically elongated slot 6| in the portion sliding in the sleeve 26. The disc r plate 361s provided with a thread passage 62 extending radially from `the periphery of the disc to its central opening which telescopes over thesleeve 26.` 'I'he wall of the sleeve 26 over which the plate 36 ilts is provided with a passage 63 (Fig. 3) which is aligned with the thread passage 62 when the plate 36 is rotatedon the sleeve 26 until the passages 62 and 63 `are Aend to end. as shown in Fig. 3.

A sleeve or lbushing 64 is disposed in this passage 63 yand projects through slot 6| into the passage 66 of the spindle 49 and the projecting end has an enlarged passage 65 at that end.

Disposed within the passage 66 in the spindle is a length of tubing 66, Figs. 2 and 3, open at its upper end. At its lower end it is turned or bent laterally as anelbow 61. The free end of the elbow has a periphery that telescopes within the enlarged passage 65 in the projecting part of` the sleeve or bushing 64. The tube 66 slides along slot 6| and serves as a key which couples the sleeve 26 and spindle 43 for rotation together while the spindle is free to slide endwise through the sleeve. 'I'he tube 66 also serves as a continuation of the bushing or sleeve 64.

Counter-sunk into the lower face of the flange 42 are .one or more permanent magnets 66, so that the outer faces of these magnets are close to butrspaced slightly above the upper face of the disc or plate 36. Similar permanent magnets 69 are counter-sunk into the upper i'acey of an annular member 16 which is secured on the upper face of the ilange 23, and which surrounds a bushing 1| that rests upon the flange 26 and has an inturned flange that bears upon the upper end of the outer race of bearing 24. 'I'he magnets 69 are disposed immediately below the magnets 66 and as close as possible to the under face of the disc 36. These magnets 66 and 69 are permanentv magnets and are disposed in similar, vertically aligned `pairs atspaced intervals about the spindle axis. Thecorrespondingly positioned ends of each pair of magnets 68 and 69 so that the north pole of each magnet `66 will be close to and above a south pole of magnet 69 of thatpair. This provides a strong magnetic attraction between the pairs of superposed magnets, and lsince the annular member 16 is secured to the flange 23 against rotation about the spindle, this magnetic attraction between the magnets 66 and 69 will yieldingly hold the member 3|, and the bobbin support 44 of which it is a part, against rotation Iwith the sleeve 26 and the spindle 43.. n

The lower end of the spindle 43I (Fig. l) is rotatably mounted in a combined radial and thrust bearing 12 carried in a small casing 13, and thus by moving the casing 13 vertically back and forth onemay elevate and lower the spindle. The.

lower end of this casing rides on a roller 14 which is rotatably'carried on a pin 15 extending laterally from a lever 16 that is pivoted on a frame 4 by a pivot pin 11. Intermediate of its ends the lever 16 carries another laterally extending pin 19 which rotatably mounts a roller cam follower 19, and thelatter rides on the periphery of a` cam 66, which is fixed on a shaft 6|. Thisshaft also `has fixed thereon a worm wheel 92. Meshed with the wheel 62 for driving it is a worm screw 66 fixed on the end of a shaft 64, which k rop tatably mounted in the frame 4. The shaft I4 on one end, carries a beveled gear 66 which meshes with and is driven by a bevel gear 66 that is attached to and is driven by a sprocket wheel 61. The wheel 61 is driven'by sprocket chain 66 from a sprocket wheel 69 which is coupled to and driven from the gear I9.

It will thusbe observed that the cam 66 will be driven at a relatively slow speed invsynchronized relation to the operation of the drawf ing rolls, and as the cam 66 rotates it will act through the lever 16 to raise and lower the spindle 49. The weight of the spindle and the housing 13 is usually suillcient to lower the spindle when the lever 16 is lowered by the cam 66, but suitable means may be provided for urging the spindle downwardly-so as to keep the housing 13 in conf tact with the roller 14 at all times. As a suitable example of each urging mechanism, the housing 13 may be provided with diametrically disposed lugs 96 and links 9| depending from the lugs 66 carry a cross bar 92 from which a weight 93 is suspended by a ring 94.

Referring now particularly to Figs. 4 to 6, the ange 23 and the annular member 16 are provided with a notch on one side, and in this notch is disposed a bell crank lever 95 mounted on a pivot pin 96 of -a bearing boss 91 attached to the upper face of the ilange 23 to which it is secured, such as by screws 91A. One arm 96 of the lever 95 lmounts in its upper face one of the permanent magnets 69, see Fig. 6, and the support 2| below lever 95 with a recess99 into whichthe lower arm 96 may swing by gravity when the magnetic pull ceases on that particualr magnet 69 which is carried by the lever 95. 'I'he bell crank lever is held normally in its full line position shown in Figs. 4 and 6 by the magnetic attraction between its magnet 69 and the permanent magnet 66 immediately above it.

When the bell crank lever 95 is in its full line position shown in Fig. 6, a nose |66 on the upper end of the other arm of that lever will be held away from the disc or plate 36, but if the bobbin support and its flange 42 lshould start to rotate a magnet 66 will move from its position above the magnet 69 on the arm 95, and when this occurs the magnetic attraction on the magnet 69.

carried by the lower end of the bell crank lever is relieved 'and that lever will at once rotate into the dash line position shown in Fig. 6 and full line position shown in Fig. 5, which will carrythe nose |66 into a position above the upper face of the plate or disc 36 and against the periphery of the flange 42. The periphery of this flange 42 is provided with notches |6| and |62 so as to provide shoulders |63 at the ends of the notches. When the nose |66 is in'the dash line position shown in Fig. 6, which is the full line position shown in Fig. 5, the nose |66 will be in the path of travel of the shoulders |63, and the engagement of a shoulder |63 sidewise against the nose |66 of the lever 95 will positively prevent further rotation of the member 9| and the bobbin-sup! port 44.

In `the operation of the illustrated mechanism,` and lassuming that the parts are assembled and connected as shown in the drawings, the yarn 9 from the drawing rolls I will pass through the guide eye |6 to the outer end of the thread passage 62 in the disc or plate 36, and then co n, ducted along that passage and through the sleeve or bushing 64 into the elbow 61 vof the tube 66, then upwardly through tube 66 into and along 7 A the e Il of the spin then-into and along the passage of the tube Il and through the opening Il of the upper end of the cap Il. The yarnl` or thread then passes over the side of the cap Il as shown in Fig. l, downwardly Past the ring II. to one of the eyes Il, then through that eye and to the bobbin to which it isattached. The

thread may beveasily threaded through the passages in the plate 3l and the spindle and other similar passages. by first inserting an end of the thread into one end of the passage through which it is to be passed and then blowing a jet of air along the passage from that same end. which will carry the thread through the passage and ,out of the top of the cap Il.

crank lever Il in this full line position determined by engagement of the upstanding arm of the lever with the end of the slot of this bearing in which it is mounted. and the magnetic pull between the magnets o f the superposed pairs, will prevent rotation with sleeve 26 of the flange 42 of the member l I and the bobbin support. There will be sufficient friction in the bearings 52 and Il of the cap 5I to cause, when the spindle is rotated, a rotary torque Aon the cap ll in the same direction as the rotation of the spindle. This rotary torque will tend to rotate the eyes Il which are supported below the cap and thus carry the yarn or thread around the bobbin as rapidly as it is released by the drawing rolls, twisted and conducted from the cap Il to'one of the eyes Il.

When the shaft Il is driven from the motor -or other source of power, the drawing rolls will be operated to draw and combine the rovings 1 and l into the yarn l, and the yarn I will thus be fed continuously through the eye or guide Il which is axially aligned above the upper end of the spindle. The yarn l then passes downwardly to the outer end of the thread passage l! in the plate 3l, then upwardly through the spindle and bobbin, over the cap 5l, downwardly through a thread guide or eye Il. and then is wound on the bobbin. it the same time the shaft l! rotates the sleeve 26 at a relatively high speed compared to the speed of the drawing mils. and also rotates the cam 8l at a relatively much lower rate. The sleeve 26 rotates the spindle 43 because of the sliding coupling between the two lthrough the sleeve or bushing Il, and, as the spindle rotates, the cam Il slowly raises and lowers the spindle in a manner to wind the thread. yarn or bundle of ilbers on the bobbin in progressive turns and in superposed layers.

The yarn l passes downwardly to the winding device 2l, is rotated about the axis of the spindle I3 to form a balloon, and the lbobbin and winding mechanism are within this balloon. This asian;

theyarn9.winditonthebobbinandpulltbe yarn through the spi-indie. The amount of friction in the rotatable mounting of the cap Il on vthe spindle determines the turning torque on position of Fig. 5, so asl to position the nose Ill in the path oi a shoulder |08 of the peripheral flange 42. This will immediately stop further rotation of the bobbin. The bell crank lever engages against a shoulder I of the support therefor, which limits the upward movement of the arm Il and the magnet'l! to the position shown in full lines in Fig. 6. A stop lll in oneof the walls of the recess il *is engaged by the arm Il when the bell crank lever turns into the dash line position of Fig. 6, and prevents the nose from bearing or riding on the disc 36, but holds it in the path of a shoulder III.

In the absence of a generic term, the expression bundle of textile fibers" is intended to include within its scope, yarns and rovings of textile 1ibers, threads, strands, and groups of filaments brought together side by side to form a thread or yarn. The twisting and winding apparatus is useful for the twisting and winding oi' any of provides a two for one twist of the yarn or fibersv l, andthe yarn 94 is wound on the bobbin as rapidly as it passes upwardly through the spindle.

As the spindle rises and falls so will the cap il, the sleeve 55, the arms 56 and Il, and the thread guide eyes 5I. The friction in the bearings in the cap Il provides sunlcient turning torque on such yarns, rovings, threads. groups of iilaments and bundles of fibers, but when such mechanism .is employed with drawing rolls. as shown, then,

of course, the expression bundle of textile ilbers is intended to refer only to staple bers in the form oi' yarns or rovings.

It will be obvious that various changes in the details, materials, and arrangement of parts, which have been herein described and illustrated in order to explain the nature of the invention. may be made by those skilled in the art within the principle and scope of the invention as expressed in the appended claims.

We claim:

l. In a winding-and twisting device. the combination of a main support, an upstanding sleeve carried by said support for rotation about its longitudinal axis, a spindle passing through and slidable endwise in said sleeve and having a threaded passage from its open upper end to the portion within said sleeve. a disc-like member telescoped over said sleeve and havinga thread passage from its outer periphery to its aperture receiving said sleeve. said sleeve having a thread passage aligned with the thread passage of said disc and extending to the passageof the sleeve. said sleeve and spindle having a sliding coupling by which the spindle rotates with the sleeve and is also slidable-within the sleeve during such rotation, a bobbin support rotatably mounted on said sleeve above said disc and having at its lower end a ange extending close to but slightly spaced from the upper face of said disc, a permanent magnet mounted on the underi'ace oi said ilange, a lever pivoted on saidsupport outwardly beyond the outer peripheryof said disc. one arm of the lever extending beneath said member and carrying a permanent magnet disposed beneath and directly opposite the permanent magnet of said bobbin support and free -to drop when magnetic attraction ceases. the other arm of said the cap from the spindle to exert a slight pull on support having a nose movable against said bob- 9 bin support when the lever rocks in a direction to carry its said permanent magnet away from said member, said bobbin support having a shoulder engageable by said nose when the nose moves against the bobbin support for stopping rotation of said bobbin support with the'sleeve when the magnet on the bobbin support is out of magnetic attraction with said lever-carried magnet.

2. A device for twisting a long, slender bundle of textile bers and winding the twisted bundle on a bobbin or form, which comprises a bobbin support having an opening from-end to end and formed on its exterior periphery to receive and hold a bobbin telescoped thereover, and mounted for rotation about the longitudinal axis of said opening, a member sliding endwise through,'and rotating in said opening, and having a passage extending longitudinally thereof from an open end thereof, and intermediate of its ends and outside of said support having an outwardly opening conduit rotating therewith, means for guiding said'bundle endwise from beyond said open end of said member, past said support and into said conduit, for movement endwise into and along said passage to the open e'ndthereof, a windingelement rotatably mounted on the open end of said member, movable endwise with said member and carrying a thread guide at one side of said bobbin support forguiding the bundle from the open end of said member to a bobbin on `said support, means for rotating said member while it is freeto move endwise, means for caus- Y tion, between said guiding means and said member, for holding said bobbin support from rota- `tion about'said axis, a safety stop yieldingly urged into a position to positively stop rotation of said bobbin support, and magnetic means cartied partly by said bobbin support and partly by .said stop, for magnetically holding said stop in non-stopping position, and releasing said stop automatically by rotary movement of said bobbin support.

3. A device for twisting a long, slender bundle ol textile bers and winding `the twisted bundle onabobbinortomwhichcomprisesabobbin l support having an opening from end to end and formed on its exterior periphery to receive and hold a bobbin telescoped thereover, and mounted for rotation'about the longitudinal axis of said end of said member, past said support and into said conduit, for movement endwise into and along said passage to the open end thereof, a winding element rotatably mounted on the open end of said member, movable endwise with said member and carrying a thread guide at one side of said bobbin support for guiding the bundle from the open end of said member to a bobbin on said support, means for rotating said member while it is free to move endwise, means for causing movement of said member back and forth endwise during its rotation, a magnetic holding unit having one part carried by said bobbin support. a stop element mounted for movement into and out oi a position in which it positively stops rotation of said bobbin support.

and yieldingly urged into said position, another part of said unit carried by said stop element and eiective by the magnetic pull between the parts. when said stop element is out of said position. to hold said stop element out of said position.

EDWARD C. PFEFFER, Ja. JOHN J. GANNON. JOHN J. FISCELLA.

REFERENCES CITED' The following references are of record in the iile of this patent:

UNITED STATES PATENTS 

